Date   : Wed, 16 Sep 2009 11:36:40 +0100
From   : jumbos.bazzar@... (Mark Haysman)
Subject: No longer Mouldy Beebs

> This is the chip just above the ROMs, to the right of th CPU/VIA. Mine are 
> marked (C)Acorn and what looks like a VLi symbol? (Picture at 
> http://i743.photobucket.com/albums/xx75/dominicbeesley/vidproc.jpg)
>
> No signs of heatsinks anywhere.

The VLSI chips do not require a heatsink. From the fault you describe, it 
could also be the data bus buffer at IC14 (LS245), that can cause spurious 
things to appear on the screen and odd crashes if it starts to play up. 
Timing is critical on those, you can't even use an ALS245 in there, it must 
be an LS245. As it's in a socket it's an easy thing to try first.

Mark.